Derwin

From DoomWiki.org

He is one of Governor Mourel's lackeys in the warehouse, who arouses Mourel's ire by selling children on the black market without cutting Mourel into the deal. At one of the important plot junctions in the game, the player can choose to accept Mourel's "bloody" commission to assassinate Derwin, bringing back his ear in exchange for a prison pass from Mourel. (The other task, the "messy" one, involves destroying a power coupling which actually controls the Front's shield generators.)

If the player chooses the coupling task rather than killing Derwin, he cannot be met in the warehouse later. It is due to an invisible trigger that closes Derwin out of availability while it exposes Worner who is critical for a future mission.